Pipeline Strength Testing

Pipeline strength testing, also called Hydrostatic Pressure Testing, is a proven industry technique to confirm the strength of the pipeline, validate its safe operating pressure and identify any weaknesses for repair.

The test involves safely isolating and clearing the pipeline of all natural gas, then completely filling the pipeline with water. The water is then pressurized to a level much higher than normal operating pressure, and the test pressure is held and monitored for a minimum of eight hours. If a section of pipeline does not meet acceptable safety standards, it is replaced and then re-tested.

Inspecting Inside Pipelines

Our interior-pipeline inspection programs identify any flaws, corrosion or other damage for further inspection, repair or replacement. Two types of tools are used for these interior inspections:

Motorized camera: In some pipelines, we use high-resolution video to assess the condition of the pipeline interior, welds, and components such as valve seals.

High-tech “smart pig”: In some pipelines, we insert a high-tech tool called a “smart pig,” which uses a combination of GPS location data, magnetic feedback and other technology to confirm the thickness of the pipeline and integrity of its welds.

Automating Pipeline Valves

With automated valves, PG&E can quickly stop the flow of gas and improve response times during an emergency.

In select locations, we are automating pipelines valves so that they can be operated remotely from our 24-hour gas control center. Some of these valves will also close automatically if a significant change in pipeline pressure is detected.

Replacing Pipelines

With proper maintenance and monitoring, steel pipelines can last more than a hundred years. Still, some of our pipelines were installed before the benefits of modern manufacturing and construction techniques, or have not been designed for use with high-tech “smart pig” internal inspection tools.

Where appropriate, we’re replacing these pipelines using industry recognized and proven installation techniques.

Regulating and Reducing Pressure

We regulate pressure on our pipeline system through a series of safety measures, including pressure regulator stations and overpressure detection devices.

Over the past few years, PG&E has increased its standards for safe operations. In order to meet these new standards, we have reduced pressure in some transmission pipelines to increase the margin of safety. As we validate records, complete strength tests or replace pipeline sections, we will work with our regulators to confirm any pressure adjustments.

Modernizing Recordkeeping

We’re overhauling our pipeline records system, making sure that all records are traceable, verifiable and complete.

As part of this modernization process, we are collecting, scanning and indexing documents from dozens of PG&E field offices. This transition from paper-based record keeping toward a modern electronic data management system will help prioritize work across our system and allow employees to have improved access to data.